The release of several new grass cultivars with higher shoot density, finer texture, and greater tolerance to environmental stresses has led many golf course superintendents to think about how best to introduce these new cultivars into their greens, tee-boxes and fairways. There are two primary methods of introducing a new grass species into an established turf grass stand: total renovation and interseeding. It is traditionally thought that the most effective means to replace an old grass cultivar with a new one is through total renovation. This consists of killing or removing the established turf grass and then reestablishing the area with a new cultivar. The downside to this approach is the requirement to close the greens or fairway until the new turf is established. The reestablishing process normally takes at least a few weeks and could last as long as several months, during which time significant loss of play and hence revenue would occur.
An alternative method to total renovation of greens is a practice that is known as interseeding. In interseeding, the new, desired cultivar is introduced into an established stand of grass over a period of time. The desired result is a gradual conversion of the existing putting green, tee-box or fairway surface from that of an older cultivar to one containing the desired cultivar without as serious a disruption to the playing surface.
Traditionally, the practices used in interseeding are similar to or adapted from practices used to overseed bermuda grass greens with a cool-season turf grass during the autumn. Generally, interseeding practices consist of trying to provide the best seed-to-soil contact possible without totally destroying the established turf surface. Verticutting, aerification with multiple small incisions, solid and/or hollow tine coring, and top dressing are used in various combinations in interseeding programs. The intensity of most of these practices is generally not severe enough to significantly disrupt or limit play. Practices that attempt to limit the competitiveness of the established turf, such as using plant growth regulators or mowing at a shorter height of cut, may also be used.
Traditionally, following the mechanical preparation, the desired cultivar is broadcast or slit-seeded into the stand. The seeding rate, in many cases, is higher than the normally recommended rates for establishment. Within a few weeks of seeding, small seedlings are observed.
Unfortunately, the germinating seeds often have a difficult time competing with the existing grass population for light, water and nutrients. Currently, it is thought that in order for interseeding to be successful, the established turf grass stand would have to be severely stressed and/or a significant amount of the turf grass canopy removed. Practices such as a severe scalping of the turf may be used to reduce the competitiveness of the established turf, which often is a bent grass, to a level that the desired cultivar would have a chance. Practices that destroy the turf canopy and create open spaces generally help reduce competition from the existing bent grass plants to allow the new seedlings to have a better chance of successful development. Given the significant and the continuing amount of work that has to be done in a given area to interseed successfully, many believe that the introduction of a new cultivar is best or most expeditiously accomplished through total renovation.
In the science of turf care, many methods have been suggested which improve germination rates as well as improve survivability of established turf grasses. Many of these methods relate to bringing additional nutrients to the root zone of the grass to efficiently aid in the growth of the turf. It has long been understood that liquids can be injected into soils to reach the root zone. The injection of liquids provides a mechanism to introduce water, nutrients, fungicides, and/or pesticides into the ground and further provides a means for aeration of the soil, which also aids turf growth. A number of exemplary U.S. patents describe and illustrate such processes and equipment.
U.S. Pat. No. 4,009,666 to Russell et al. discloses an apparatus for injecting fluid below a soil or turf surface. The apparatus is comprised of a plurality of nozzles carried by a support rod; each nozzle forms a stream of fluid passing therethrough has a low friction contact surface for contacting the surface of the soil. The apparatus is provided with a pump that cooperates with the nozzle to inject fluid substantially below the soil surface.
U.S. Pat. No. 4,807,544 to Cross et al. discloses an apparatus for injecting agro-chemicals into the subsurface of the soil without tilling the soil. The high pressure pump delivers the solution to be injected into a series of injection nozzles that cause liquid jets to be formed that have sufficient velocity and narrow cross-section to inject into the soil. Included in the design is a shield-pan that minimizes clogging of the nozzles.
U.S. Pat. No. 5,407,134 to Thompson et al. discloses a liquid distribution system having a pair of variable displacement pumps for mixing chemicals and water to a desired proportion and delivering the solution to an open furrow just prior to the furrow being covered with soil.
U.S. Pat. No. 5,487,346 to Taylor discloses an apparatus for intermittently injecting liquid into soil at pressures as high as 1200 PSI and at desired flow rates of between 6 and 60 gallons per minute. An accumulator and sequencing valve is used to control the amount of fluids being injected into the ground. (Note that the apparatus shown in this patent is also shown in FIG. 1 herein.)
U.S. Pat. No. 5,503,091 to Foster et al. discloses a turf conditioning machine which disperses a high pressure stream of fluid into the ground in a vertically-aligned cylindrically-shaped drilling hole. The holes are drilled using a hydrated polymer that has absorbed and thus will release moisture in a controlled fashion.
U.S. Pat. No. 5,741,090 to Dunning et al. discloses a system and method for injecting liquids and solids into the earth. The system discloses a setup wherein only the liquid is run through the main pump while a liquid solid slurry is stored and moved to join the liquid under pressure by a chemical injector pump. A displacement wheel commands solenoid valves for pulsing the pressurized liquid into the ground surface.
Several U.S. patents disclose methods for injecting seeds or particulate matter mixed with a fluid into the ground typically through the use of a pressurized steam of liquid. Exemplary patents include the following.
U.S. Pat. No. 4,145,980 to Boots discloses an automatic seeder for planting tiny seeds at a given depth and at evenly spaced intervals. The apparatus utilizes a plurality of furrow creating mechanisms that are arranged to create furrows of a consistent desired depth in front of the seed discharging means. A spray arrangement is used to cover the disbursed seeds with water.
U.S. Pat. No. 4,218,855 to Wemmer discloses a particulate spray nozzle having an internal mixing-chamber with a liquid spray orifice. When a liquid is sprayed through the liquid supply orifice, particulate matter is drawn into the mixing chamber by a venturi facilitating the mixing of the dry material with the liquid. This material is ejected through a port on one side of the mixing chamber.
U.S. Pat. No. 4,224,889 to Cruse discloses an apparatus for sowing seeds in a liquid suspension. The liquid seed combination is discharged behind the plowshare into a furrow.
It is also known and has been shown to inject single seeds into turf or ground. U.S. Pat. No. 4,899,672 to Paul discloses a method for sowing separate seeds in a furrow made by a plowshare. The device, which trails the plowshare, traps a single seed and injects it through a nozzle into a furrow before the furrow is closed.
U.S. Pat. No. 5,303,663 to Salstrom discloses a method and apparatus for discharging water absorbent polymers into a “blanket” near the root zone of a crop plant.
U.S. Pat. No. 5,394,812 to Dunning et al. discloses an apparatus and method for dispensing a substance such as a hydrophylic polymer into a soil to minimize the need for repeated irrigation. The apparatus is contained on a trailer that supports a mixing tank within which the polymer and liquid are continuously agitated. The mixture, in a liquid form is sent through a pump to an outlet having a plurality of apertures communicating with the tank via a manifold. A series of valves operates such that high pressure pulses of the liquid polymer mixture are discharged with sufficient velocity that the slugs of material are discharged under the soil. There are still other fluid and fluid particulate injection systems, beyond those disclosed above, that utilize a venturi to mix particulate materials with fluids and inject them into the ground.
Common among all of these, to our knowledge is a lack of a system with the capability of simultaneously planting seeds by high-pressure liquid injection over a dispersed area. Further, to our knowledge, no one has used a high-pressure liquid injection system for planting seeds into an established stand of turf.
Accordingly, there is still a need for more efficient methods and systems for planting seeds into the crown area of an established stand of turf for interseeding purposes. In particular, there is a continuing need for easy-to-use, inexpensive-to-operate and non-complicated methods and systems for safely and easily accomplishing seeding of existing grass areas with less disruption to the playing surfaces to be seeded. Preferably such new methods and systems should produce near optimal results in terms of achieving desired depth of seed placement into the soil and achieving successful seed germination rates and seedling growth. Also, on a more general level, there is a continuing need to find improved methods and systems for planting seeds over large areas with less effort, reduced expenditure of energy, and reduced minimal disruption to the existing turf, vegetation or soil to be planted.
Thus, objects of the present invention include providing:    (1) a liquid/seed injection (“LSI”) system and method for simultaneously injecting multiple seeds into the turf or ground to a desired planting depth over a distributed area using high-pressure (“HP”);    (2) a high-pressure liquid seed injection (“HP-LSI”) system and method which, by the way it works, helps protects the seeds from physical damage during and after planting;    (3) an HP-LSI planting system and method which can be used to interseed, that is, plant within an existing well-established turf population;    (4) an HP-LSI planting system and method which permits a gradual, timed, introduction of new seeds into existing stands with minimal surface disruption;    (5) an HP-LSI planting system and method which allows for the planting of seeds without mechanical tillage of the soil and/or soil cover;    (6) an LSI planting system and method where the mixing of the dry seeds and the liquid can be easily and quickly accomplished in one location shortly before injection;    (7) an LSI planting system and method which subjects the coat of the seeds to be planted to an agronomically acceptable and desirable amount of scarification; and    (8) an LSI planting system and method which reduces the amount of energy and water needed to plant seeds;    (9) an LSI planting system and method which enables a large batch of seeds to be efficiently and automatically planted at a desired depth into soil over a large area, with the multiple seeds being planted simultaneously in a predetermined pattern and with the pattern being repeated and spaced at predetermined intervals from one another; and    (10) a new application for the basic high-pressure liquid pumping and injection systems now being used for high-pressure injection of liquid-soluble fertilizers, pesticides and the like, but not heretofore modified and arranged to plant seeds, thus helping make such injection equipment more versatile.